Pineal-Thyroid Cytophysiological Responsiveness to Altered Steroid Hormone and Antihormone Milieu in Rat (Rattus rattus)

Abstract

The current investigation was undertaken to assess the pineal and thyroid gland cytophysiology and function in response to an exogenously altered steroid milieu following administration of a steroid hormone and non-steroidal antihormones. In the present study male rats (Rattus rattus) were injected with estradiol at a dose of 2 mg, testosterone 100 µg, tamoxifen 100 µg and flutamide 2 mg per 100 g b.w. intramuscularly for 15 consecutive days. Control rats were similarly injected with peanut oil vehicle intramuscularly for the same duration as the treated groups. The results indicated that pineal and thyroid gland response to estradiol and testosterone administration was opposite in nature. Estradiol induced significant hypertrophy of pineal and thyroid cytophysiology as indexed from significantly increased pineal and thyroid karyomorphological and associated parameter values, testosterone contrarily caused significant atrophy of pineal and thyroid cytophysiological parameters. Tamoxifen acted as a true estrogen agonist, whereas flutamide showed an androgen antagonist nature, thereby causing hyperactivity of pineal and thyroid karyomorphological and associated functions similar to that observed in estradiol treated rats, but contrary to that shown by testosterone induction in these rats.